E-Thesis 50 views 24 downloads
Characterisation of Bio-Based Polymers for Use in the Packaging Industry / LAUREN JEFFERY
Swansea University Author: LAUREN JEFFERY
Abstract
Six polymer film samples, of unknown composition, were provided by a company called Greenlight Packaging for testing. Although the compositions were unknown to the company, as they were provided by a third party, the materials were believed to be PLA based and compostable. The conditions required an...
| Published: |
Swansea, Wales, UK
2023
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Master of Research |
| Degree name: | MSc by Research |
| Supervisor: | Korkees, Feras. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa63603 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Abstract: |
Six polymer film samples, of unknown composition, were provided by a company called Greenlight Packaging for testing. Although the compositions were unknown to the company, as they were provided by a third party, the materials were believed to be PLA based and compostable. The conditions required and capability of the films to undergo biodegradation were unknown. The company were using the films to encase starch based loose fill in order to create a biodegradable cushion to replace expanded polystyrene within the packaging industry, due to the associated difficulties with disposal. During testing, it was noted that these films also had the potential to replace polyolefin films such as low density polyethylene and polypropylene used within the packaging industry. Therefore, throughout this project the properties of the six film samples provided were compared against these two conventional polyolefin films to identify whether the films had comparative physical and mechanical properties in order for them to be considered as compostable replacements. This study analyses the thermal, mechanical, and degradation properties of the six biobased polymer films along with expanded polystyrene, low-density polyethylene film and polypropylene film as references. The material compositions were unknown as the samples were provided by a third part, and were therefore identified using Fourier-transfer infrared spectroscopy by comparing the spectra to a database, which confirmed that all films were Polylactic acid based. Differential scanning calorimetry was used to identify transition temperatures, which were in the regions of 51-72°C and152-169°C. This identifies the temperature ranges at which the films can be used and gives information regarding processing. DSC was also used to identify the oxidation induction temperatures and oxidation induction time which indicated the materials had low thermal stability. Water and oil permeation tests were conducted to establish the barrier properties of the materials. This gave information on whether the material could be used for packaging applications where good barrier properties are required against water and oil. Results concluded that the polyolefins had much better barrier properties against water compared to the biopolymers, although all polymers tested performed similarly with oil as the permeant. Mechanical properties were measured through the use of tensile and tear tests. Samples were also subjected to various conditioning to simulate environmental factors such as freezing, thawing, and being subjected to elevated temperatures and humidity, during storage. The tear strength was then measured again after conditioning and values were compared to identify if conditioning caused any degradation and therefore reduction in strength. Very small changes were observed in the strength of the polymers after conditioning the samples. The stresses, strains, and tear and tensile strengths varied throughout the polymers. The film was originally developed to encase starch polymer peanuts to form a cushion to be used as a substitute for expanded polystyrene (EPS). Therefore, the thermal conductivity of the films was measured and compared to values for EPS to ensure there was no interference in the insulating properties of the peanuts by the polymer films. All values were similar to that of EPS. The composting of the films was monitored over periods of 3, 6, 9, and 12 months. Samples were also left for 336 hours in an accelerated weathering tester prior to composting for 180 days to identify how UV exposure affects the degradation of materials. |
|---|---|
| Keywords: |
Biodegradable, Compostable, Mechanical, Polylactic Acid, Polymers, Properties |
| College: |
Faculty of Science and Engineering |